<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<p id="demo"></p >		<!-- 此段落内容由js代码动态添加 -->
	</body>
	<script>
		document.getElementsByTagName("p")[0].innerHTML = "你好，欢迎你";
	</script>

</html>